The ring on the left hand of the man who is being interrogated in the beginning of the episode disappears briefly during a closeup of the shackles around his wrist.
The person about to be interrogated just before the opening credits appears to be in an anechoic chamber going by the way the walls and ceiling are structured.
But the sounds the interrogator makes whilst opening the door and with his footsteps have very distinct echoes. In an anechoic chamber these echoes wouldn't be heard at all or would at the very least be much less pronounced.